Such transport chains are primarily used in wood processing machines, whereby the workpieces that are to be carried by the transport chains are furniture components, boards for interior construction, or other boards made of wood or wood-like materials used in the construction industry. The continuous processing machines intended for such purposes are designed with ever increasing conveyor speeds, resulting in increased wear problems. The chain links, provided with track rollers and guide rollers, are subject to uncontrollable snaking movements, which considerably affect the proper rolling movement of the track rollers and guide rollers in the guide profiles and typically extend not only along the upper run of the conveyor chain but also along the return area at the sprocket wheels.
The troublesome vibrations are attributed primarily to the fact that as the transport chain runs around the sprocket wheels, it assumes the shape of a polygon into which and from which the individual chain links must be deflected due to the otherwise linear position. Pulsating tensile forces are acting especially on the drive sprocket wheel because of the polygon effect. The vibrations induced in this manner in the transport chain prevent the track rollers and guide rollers of the chain links from being in uniform contact with the tracks of the guide profile of the guide rails and instead lift off sporadically and then strike down on it again. The accelerating and decelerating forces associated with this action as well as the abrupt forces impacting the rollers, the guide profiles and the sprocket wheels lead to great wear of these components and their assemblies within a short period, leading to a breakdown of the transport system. The troublesome vibrations are additionally promoted by a loose, hanging return of the lower run of the transport chain.
Already recommended was a magnetic chain steering system for high-speed transport chains, where permanent magnets are integrated in the guide rail immediately adjacent to the tracks for the track rollers of the chain links. The magnetic circuit of the permanent magnets closes across the tracks and the rolling track rollers of the chain link, whereby an air gap is provided between the outer face of the track rollers and a web at the guide rail, which is located to the side of the track in a protruding manner. Since the track rollers touch the track of the guide rail in an essentially linear manner, and the magnetic forces in the air gap act axially parallel upon the track rollers of the chain link, no optimal conditions for damping the vibrations of the transport chain are created with this type of magnetic chain steering.
It is, therefore, the objective of the invention to create a chain guide system of the kind mentioned above, where good vibration damping of the transport chain is achieved using magnetic forces.